$ git clone -n https://src.fedoraproject.org/rpms/R-XML.git /var/lib/mock/f38-build-724201-99404/root/chroot_tmpdir/scmroot/R-XML
Cloning into '/var/lib/mock/f38-build-724201-99404/root/chroot_tmpdir/scmroot/R-XML'...
$ git fetch origin 01766dd44ab6081a35df38cc4e19b5371ce512d3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-XML
 * [new ref]         01766dd44ab6081a35df38cc4e19b5371ce512d3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 01766dd R-maint-sig mass rebuild